527.8km ultra-long single span distributed optical sensing with Co-Propagating 400Gb/s optical transmission

The longest span of 527.8km distributed sensing of temperature and vibration measurement with $400 \mathrm{~Gb} / \mathrm{s}$ data transmission is reported, based on bidirectional sensing configuration and ROPA technology. Removing the communication signal, the distance can be further extended to 551.1 km.